From 3ea8529acc30467331b7b1f5da6cf668fac091c7 Mon Sep 17 00:00:00 2001 From: Petr Štetiar Date: Tue, 19 Apr 2016 19:42:07 -0500 Subject: PCI: imx6: Add reset-gpio-active-high boolean property to DT MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Currently the reset-gpio DT property which controls the PCI bus device reset signal defaults to active-low reset sequence (L=reset state, H=operation state) plus the code in reset function isn't GPIO polarity aware - it doesn't matter if the defined reset-gpio is active-low or active-high, it will always result into active-low reset sequence. I've tried to fix it properly and change the reset-gpio reset sequence to be polarity-aware, but this patch has been accepted and then reverted as it has introduced few backward incompatible issues: 1. Some DTBs, for example, imx6qdl-sabresd, don't define reset-gpio polarity correctly: reset-gpio = <&gpio7 12 0>; which means that it's defined as active-high, but in reality it's active-low; thus it wouldn't work without a DTS fix. 2. The logic in the reset function is inverted: gpio_set_value_cansleep(imx6_pcie->reset_gpio, 0) msleep(100); gpio_set_value_cansleep(imx6_pcie->reset_gpio, 1); so even if some of the i.MX6 boards had reset-gpio polarity defined correctly in their DTSes, they would stop working. As we can't break old DTBs, we can't fix them, so we need to introduce this new DT reset-gpio-active-high boolean property so we can support boards with active-high reset sequence. This active-high reset sequence is for example needed on Apalis SoMs, where GPIO1_IO28, used to PCIe reset is not connected directly to PERST# PCIe signal, but it's ORed with RESETBMCU coming off the PMIC, and thus is inverted, active-high. Tested-by: Tim Harvey # Gateworks Ventana boards (which have active-low PERST#) Signed-off-by: Petr Štetiar Signed-off-by: Bjorn Helgaas Reviewed-by: Lucas Stach Acked-by: Rob Herring --- Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'Documentation/devicetree/bindings') diff --git a/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt b/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt index 0561e88f3b37..636707df0952 100644 --- a/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt +++ b/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt @@ -19,6 +19,12 @@ Optional properties: - fsl,tx-deemph-gen2-6db: Gen2 (6db) De-emphasis value. Default: 20 - fsl,tx-swing-full: Gen2 TX SWING FULL value. Default: 127 - fsl,tx-swing-low: TX launch amplitude swing_low value. Default: 127 +- reset-gpio: Should specify the GPIO for controlling the PCI bus device reset + signal. It's not polarity aware and defaults to active-low reset sequence + (L=reset state, H=operation state). +- reset-gpio-active-high: If present then the reset sequence using the GPIO + specified in the "reset-gpio" property is reversed (H=reset state, + L=operation state). Additional required properties for imx6sx-pcie: - clock names: Must include the following additional entries: -- cgit v1.2.3